/Engine/Plugins/Experimental/PCG/Source/PCG/Public/Elements/PCGAttributeTransferElement.h
To do the same but with a Source param data, use CreateAttribute.
[UCLASS](Programming/UnrealArchitecture/Reference/Classes#classdeclaration)(BlueprintType, ClassGroup=(Procedural)) class UPCGAttributeTransferSettings : public [UPCGSettings](API\Plugins\PCG\UPCGSettings)
FPCGAttributePr...
SourceAttributeProperty
FPCGAttributePr...
TargetAttributeProperty